This invention relates generally to power drives for vehicular doors, and more specifically to drive systems employing rotary, helical drive members including primary and secondary mechanical door locks directly actuated by the helical drive.
Rotary helical drives for vehicular doors are typically disclosed in U.S. Pat. Nos. 5,077,938, and 3,745,705. The operators in these references employ rotary drives utilizing ball screw driven members or drive nuts and include various means of locking the associated vehicular doors.
Drive systems for vehicular doors utilized on mass transit vehicles must satisfy particular operating requirements specific to those vehicles. These requirements include positive, and in some cases, redundant mechanical lock systems, capable of insuring that doors remain closed and operable during car travel and any other car location other than predetermined passenger discharge areas. Additionally, it is required that doors can be manually opened through the use of an emergency release system which allows unlocking the door and manually forcing the doors from closed to an open position.
Door locking is particularly difficult with the rotary, helical drive, since the door is moved by a nut or moving member traveling on a threaded rod. With this system, any failure of the drive nut or motor actuated rotating threaded shaft can result in a free-wheeling door, or an ability to manually or back-drive the operator to a door open position.
Presently used drive systems typically include complicated and expensive auxiliary mechanisms to provide locking means external or ancillary to the drive system.
The invention disclosed herein features relatively simple lower cost primary and secondary locks directly driven by the rotating helical threaded drive member. Additionally, in the preferred embodiment, the invention disclosed herein is capable of supporting the driven door in addition to driving it from open to closed positions. While the rotary locks disclosed herein are shown in a configuration having direct door support, application of the lock to door systems utilizing separate door hangers is contemplated. Lock operation with or without a separate hanger is equivalent.
Accordingly, it is an object of this invention to provide a power door drive for mass transit vehicles utilizing a rotary, helical drive system having primary and secondary mechanical door locks directly operated by the helical drive.
It is an additional object of this invention to provide a rotary, helical door drive system for mass transit vehicles wherein the helical drive member carries the driven door.
It is a further object of this invention to provide a rotary, helical door drive system for mass transit vehicles wherein a primary lock is an integral part of the helical drive and driven nut.
It is a further object of this invention to provide a power door operator having a rotary, helical drive system wherein a secondary lock is integral in the helical drive and nut components.
It is a further object of this invention to provide an overdoor mounted rotary helical drive operator providing mounting bracket which will compensate for deflections and variations in the vehicle mounting structure.